Explainable artificial intelligence models for predicting risk of suicide using health administrative data in Quebec

Suicide is a complex, multidimensional event, and a significant challenge for prevention globally. Artificial intelligence (AI) and machine learning (ML) have emerged to harness large-scale datasets to enhance risk detection. In order to trust and act upon the predictions made with ML, more intuitive user interfaces must be validated. Thus, Interpretable AI is one of the crucial directions which could allow policy and decision makers to make reasonable and data-driven decisions that can ultimately lead to better mental health services planning and suicide prevention. This research aimed to develop sex-specific ML models for predicting the population risk of suicide and to interpret the models. Data were from the Quebec Integrated Chronic Disease Surveillance System (QICDSS), covering up to 98% of the population in the province of Quebec and containing data for over 20,000 suicides between 2002 and 2019. We employed a case-control study design. Individuals were considered cases if they were aged 15+ and had died from suicide between January 1st, 2002, and December 31st, 2019 (n = 18339). Controls were a random sample of 1% of the Quebec population aged 15+ of each year, who were alive on December 31st of each year, from 2002 to 2019 (n = 1,307,370). We included 103 features, including individual, programmatic, systemic, and community factors, measured up to five years prior to the suicide events. We trained and then validated the sex-specific predictive risk model using supervised ML algorithms, including Logistic Regression (LR), Random Forest (RF), Extreme Gradient Boosting (XGBoost) and Multilayer perceptron (MLP). We computed operating characteristics, including sensitivity, specificity, and Positive Predictive Value (PPV). We then generated receiver operating characteristic (ROC) curves to predict suicides and calibration measures. For interpretability, Shapley Additive Explanations (SHAP) was used with the global explanation to determine how much the input features contribute to the models' output and the largest absolute coefficients. The best sensitivity was 0.38 with logistic regression for males and 0.47 with MLP for females; the XGBoost Classifier with 0.25 for males and 0.19 for females had the best precision (PPV). This study demonstrated the useful potential of explainable AI models as tools for decision-making and population-level suicide prevention actions. The ML models included individual, programmatic, systemic, and community levels variables available routinely to decision makers and planners in a public managed care system. Caution shall be exercised in the interpretation of variables associated in a predictive model since they are not causal, and other designs are required to establish the value of individual treatments. The next steps are to produce an intuitive user interface for decision makers, planners and other stakeholders like clinicians or representatives of families and people with live experience of suicidal behaviors or death by suicide. For example, how variations in the quality of local area primary care programs for depression or substance use disorders or increased in regional mental health and addiction budgets would lower suicide rates.

HEPCIDIN AND IRON BIOMARKERS MODULATED IN HEMODIALYSIS PATIENTS

Chronic kidney disease (CKD) describes abnormal kidney function and/or structure. It is common, frequently unrecognized, and often exists together with other conditions.Aim - to investigate the role of serum hepcidin in inflammation among hemodialysis patients with chronic kidney disease (CKD).This prospective hospital-based study conducted in Kirkuk city included 30 CKD patients undergoing regular hemodialysis at Kirkuk General Hospital, along with 30 healthy individuals as controls. Blood samples were collected before and after hemodialysis, as well as from the control group, and analyzed for various parameters. The blood samples were collected for determination of hepcidin levels were determined using Enzyme-Linked Immunosorbent Assay, while S. iron, total iron-binding capacity (TIBC).The study found that HD patients had significantly higher levels of serum hepcidin compared to the control group. The mean serum hepcidin level in HD patients was 246.1±72.4 ng/ml, while in the control group, it was 105.7±20.2 ng/ml. Serum ferritin levels were also found to be significantly higher in HD patients compared to the control group (430.5±148.3 ng/ml vs. 153.8±60.6 ng/ml). HD patients had lower serum iron and total iron-binding capacity (TIBC) levels compared to the control group (63.10±15.62 µg/dl vs. 92.98±26.68 µg/dl and 265.4±61.1 µg/dl vs. 273.3±65.9 µg/dl, respectively). After dialysis, both serum hepcidin levels decreased, with the mean serum hepcidin decreasing from 246.1±72.4 ng/ml to 206.3±61.8 ng/ml The study also demonstrated a positive correlation between hepcidin levels serum ferritin, urea, and creatinine, and a negative correlation with serum iron and hemoglobin levels in patients before hemodialysis.HD patients have higher levels of serum hepcidin, ferritin, iron and TIBC, suggesting potential involvement in inflammation and iron metabolism dysregulation.

The prevalence of IGM antibodies to Zika virus in pregnant women in Northern Nigeria

INTRODUCTION

Zika virus (ZIKV) infection during pregnancy can result in severe outcomes for both the pregnant woman and the developing fetus. The objective of this study was to investigate the prevalence of Zika virus infection among pregnant women who sought healthcare services at Ahmadu Bello University Teaching Hospital.

MATERIALS AND METHODS

Serum samples were collected and analyzed using Enzyme Linked Immunoassay and RT-qPCR methods, while a structured questionnaire was used to gather relevant information about the participants.

RESULTS

The results showed that 53 out of the 180 pregnant women tested positive for Anti-Zika IgM antibodies, which represents a 29.4% prevalence rate. Subsequent RT-qPCR analysis found that only 6 out of the 53 positive samples contained Zika virus RNA. Fever and headache were the most commonly reported symptoms related to the infection.

CONCLUSION

These findings indicate a potential outbreak of Zika fever in Northern Nigeria emphasizing the importance for pregnant women to take precautions to avoid getting infected.

A case-control study on predicting population risk of suicide using health administrative data: a research protocol

INTRODUCTION

Suicide has a complex aetiology and is a result of the interaction among the risk and protective factors at the individual, healthcare system and population levels. Therefore, policy and decision makers and mental health service planners can play an important role in suicide prevention. Although a number of suicide risk predictive tools have been developed, these tools were designed to be used by clinicians for assessing individual risk of suicide. There have been no risk predictive models to be used by policy and decision makers for predicting population risk of suicide at the national, provincial and regional levels. This paper aimed to describe the rationale and methodology for developing risk predictive models for population risk of suicide.

METHODS AND ANALYSIS

A case-control study design will be used to develop sex-specific risk predictive models for population risk of suicide, using statistical regression and machine learning techniques. Routinely collected health administrative data in Quebec, Canada, and community-level social deprivation and marginalisation data will be used. The developed models will be transformed into the models that can be readily used by policy and decision makers. Two rounds of qualitative interviews with end-users and other stakeholders were proposed to understand their views about the developed models and potential systematic, social and ethical issues for implementation; the first round of qualitative interviews has been completed. We included 9440 suicide cases (7234 males and 2206 females) and 661 780 controls for model development. Three hundred and forty-seven variables at individual, healthcare system and community levels have been identified and will be included in least absolute shrinkage and selection operator regression for feature selection.

ETHICS AND DISSEMINATION

This study is approved by the Health Research Ethnics Committee of Dalhousie University, Canada. This study takes an integrated knowledge translation approach, involving knowledge users from the beginning of the process.

Validity of CHA2DS2-VASc score in patients with malignancies

Introduction

Anticoagulation for patients with atrial fibrillation/flutter (AF) after risk stratification based on CHA2DS2-VASc score (congestive heart failure, hypertension, age group, Diabetes Mellitus, prior stroke, transient ischemic attack or thromboembolism, prior heart attack, peripheral artery disease or aortic plaque and patient's gender) has been the gold standard practice to prevent cerebrovascular accidents (CVA).

Purpose

Since patients with malignancies are at increased risk of thrombophilia, we tried to study if cancer patients with atrial fibrillation are at increased risk for CVA beyond what should be expected based on their comorbidities.

Methods

We used the Nationwide Readmissions Database (NRD) database for the years 2016–2019. First, we extracted all cases with a diagnosis of atrial fibrillation/flutter. Exclusion criteria included patients younger than 18-year-old. We studied the comorbidities and calculated CHA2DS2-VASc score. Then, we compared the risk for admission with an acute CVA in patients with and without any diagnosis of malignancies (solid cancer, leukemia, lymphoma or metastatic disease). Patients with carcinoma in situ were considered non-cancer patients. Corrected logistic regression and Chi-square tests using survey procedures in SAS 8.1 were applied to accommodate for complex sampling (Rao-Scott design).

Results

We identified 1,748,619 weighted admissions with AF equally distributed across the years. 5% were patients with malignancies. The mean age was 74-year-old for cancer patients and 71-year-old for non-cancer patients with quite equal gender distribution (43–49% were female). Patients with a diagnosis of cancer has high inpatient mortality (13%). Every additional point in CHA2DS2-VASc score was associated with increased odds of admission with CVA. Having a diagnosis of cancer was not associated with increased odds of admission with CVA (odd ratio for 95% confidence interval 1.0 [0.95–1.1]). Patients with history of VTE (assuming they are on anticoagulation) or who are on chronic anticoagulation have lower risk of admission with acute CVA if they have AF.

Conclusions

Although malignancies is associated with hypercoagulable status including higher risk for stroke, deep venous thrombosis and pulmonary embolism, our cross-sectional study indicates that CHA2DS2-VASc score is still a reliable tool for risk stratification in patients with atrial fibrillation. More longitudinal studies are needed.

Funding Acknowledgement

Type of funding sources: None.

Effect of the renin angiotensin system inhibitors on inflammatory markers: a systematic review and meta-analysis of 32 randomized controlled trials

Background

Inflammation plays a critical role in the etiology of cardiovascular disease (CVD). The renin-angiotensin system inhibitors including angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) have been shown to be effective in reducing elevated blood pressure. However, the information on their potential effect on inflammatory markers including C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) is still lacking.

Purpose

We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to synthesize evidence about effect of ACEIs and ARBs on selected inflammatory markers.

Methods

PubMed, Scopus, and Embase were searched from inception until February 15, 2021. We included RCTs that assessed the effect of ACEIs or ARBs, compared with placebo, on any of the following markers: CRP, IL-6, or TNF-α. Mean changes in the relevant markers levels were pooled as a standardized mean difference (SMD) with a 95% confidence interval (CI) under the random-effects model. Heterogeneity was assessed using I2 and χ2 tests.

Results

Thirty-two RCTs (n=3,403 patients) were included in the analysis. Overall pooled analysis suggested that ACEIs significantly reduced plasma levels of CRP (SMD: −1.08 [95% CI: −1.57 to −0.59]; I2: 95%), IL-6 (SMD: −0.75 [95% CI: −1.41 to −0.09]; I2: 81%), and TNF-α (SMD: −1.77 [95% CI: −2.82 to −0.73]; I2: 95%). This lowering effect remained statistically significant by perindopril in terms of all relevant markers, by quinapril and ramipril in terms of IL-6 and by enalapril in terms of TNF-α. As for the ARBs as a class, they showed a statistically significant reduction only in terms of CRP (SMD: −0.14 [95% CI: −0.28 to −0.01]; I2: 0%) and did not significantly affect any of the other markers. Moreover, the ARBs individual drugs did not show any significant effect on any of the relevant markers except for valsartan that significantly reduced plasma levels of IL-6 (SMD: −0.42 [95% CI: −0.80 to −0.04]; I2: 0%).

Conclusions

Based on the results of this meta-analysis, ACEIs showed a beneficial lowering effect on CRP, IL-6, and TNF-α, while ARBs were effective as a class only in terms of CRP reduction. Further larger RCTs are warranted to confirm these results particularly in case of individual drugs and to assess the significance of these reductions in terms of CVD prevention.

Funding Acknowledgement

Type of funding sources: None.

Association of statin use in older people primary prevention group with risk of cardiovascular events and mortality: a systematic review and meta-analysis of observational studies

Background

Current evidence from randomized controlled trials on statins for primary prevention of cardiovascular disease (CVD) in older people, especially those aged >75 years, is still lacking.

Purpose

We conducted a systematic review and meta-analysis of observational studies to extend the current evidence about association of statin use in older people primary prevention group with risk of CVD and mortality.

Methods

PubMed, Scopus, and Embase were searched from inception until March 18, 2021. We included observational studies (cohort or nested case-control) that compared statin use vs non-use for primary prevention of CVD in older people aged ≥65 years; provided that each of them reported the risk estimate on at least one of the following primary outcomes: all cause-mortality, CVD death, myocardial infarction (MI), and stroke. Risk estimates of each relevant outcome were pooled as a hazard ratio (HR) with a 95% confidence interval (CI) using the random-effects meta-analysis model.

Results

Ten observational studies (9 cohort and one case-control study; n=872,845) fulfilled our criteria. The overall combined estimate suggested that statin therapy was associated with a significantly lower risk of all-cause mortality (HR: 0.86 [95% CI: 0.79 to 0.93]), CVD death (HR: 0.80 [95% CI: 0.78 to 0.81]), and stroke (HR: 0.85 [95% CI: 0.76 to 0.94]) and a non-significant association with risk of MI (HR: 0.74 [95% CI: 0.53 to 1.02]). The beneficial association of statins with the risk of all-cause mortality remained significant even at higher ages (>75 years old; HR: 0.88 [95% CI: 0.81 to 0.96]) and in both men (HR: 0.75 [95% CI: 0.74 to 0.76]) and women (HR: 0.85 [95% CI: 0.72 to 0.99]). However, this association with the risk of all-cause mortality remained significant only in those with DM (HR: 0.82 [95% CI: 0.68 to 0.98]) but not in those without DM.

Conclusions

Statin therapy in older people (aged ≥65 years) without CVD was associated with a 14%, 20% and 15% lower risk of all-cause mortality, CVD death and stroke, respectively. The beneficial association with the risk of all-cause mortality remained significant even at higher ages (>75 years old), in both men and women, and in individuals with DM, but not in those without DM. These observational findings support the need for trials to test benefits of statins in those above 75 years of age.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Results of the meta-analysis

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron–positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation operator sensitive to CPT-violating effects. We find no violation at the precision level of 10⁻⁴, with an over threefold improvement on the previous measurement.

CPT violation could manifest itself in annihilating positronium events, but searching for this effect would require to know the spin of the annihilating system. Here, the authors do this using a positron-emission tomography scanner, finding no violation with a statistical precision of 10⁻⁴.

Neutropenia in patients under treatment with clozapine and COVID-19 infection

Introduction

Clozapine is among the most effective antipsychotics used for treatment resistant schizophrenia. Adverse reactions to clozapine include neutropenia. Case series report that clozapine-treated patients with COVID-19 have no documented neutropenia.

Objectives

We sought to investigate the potential adverse effect of coronavirus disease (COVID-19) in patients taking clozapine.

Methods

We retrospectively inspected data of 13 consecutive patients on clozapine, admitted to Highgate Mental Health Centre -Camden & Islington NHS Foundation Trust between March and June 2020. Selection was based on their COVID-19 symptoms presentation and/or COVID-19 positive test. We used a linear regression model with COVID status as independent variable and absolute neutrophil count (ANC) as dependent variable to inform about a correlation between COVID-19 status and neutrophil count. STATA was used for statistics.

Results

We collected data on thirteen patients of which nine were male. The median age was of 41.97 years; six subjects were Black, three were Asian and four were White Caucasian. Ten subjects tested positive to COVID-19 and 3 were suspected cases -these latter were excluded from stastical analysis. During COVID-19 infection, neutrophils count (ANC) dropped significantly to 4.215 from a baseline value of 5.337. The beta values of 0.83 shows that ANC declined significantly during COVID-19 infection (p =<.0001, R2 = 95%). In three of thirteen patients, ANC drop was significant and changed the patients’ monitoring status from green to amber and required frequent blood tests.

Conclusions

Clinicians should bear in mind that a significant drop in neutrophils count may occur in COVID-19 -infected patients taking clozapine.

Disclosure

No significant relationships.

Knowledge assessment of snake antivenom among healthcare practitioners involving educational intervention in northern Nigeria: a study protocol

Introduction

Snakebite envenoming (SBE) is an important occupational and public health hazard especially in sub-Saharan Africa. For optimum management of SBE, adequate knowledge of Snake antivenom (SAV) is very critical among the healthcare practioners in this region. Information related to the knowledge of SAV use in the management of SBE, as well as SAV logistics is scarce among the Health Care Professionals (HCPs) in Nigeria, particularly in the northern region. We therefore aimed to develop, validate and utilize a tool to assess the SAV knowlegde among HCPs in northern Nigeria. We also sought to implement and evaluate an intervention that could improve the SAV knowledge among the HCPs.

Methods

The proposed study will be conducted in three phases: Phase I will involve the development of the item-pool to be included in the tool, followed by a face, content validity and construct validity. The tool reliability, readability and difficulty index will be determined. Phase II will involve the utilization of the tool to assess baseline SAV knowledge among the HCPs followed by an educational intervention. Multiple Linear Regression analysis will be used to determine the factors associated with SAV knowledge among the HCPs. Lastly, Phase III which will be a repeat of Phase II to assess and evaluate the knowledge after the intervention.

Discussion

The study design and findings may guide future implementation and streamline the intervention of improving SAV knowledge in HCPs training and practice.

Lay Summary

Knowledge assessment and educational intervention of snake antivenom among healthcare practitioners in northern Nigeria: a study protocol Snakebite envenoming (SBE) is an important occupational and public health hazard especially in sub-Saharan Africa. For optimum management of SBE, adequate knowledge of snake antivenom (SAV) is very critical among the healthcare practitioners. The baseline knowledge SAV dosage, mode of administration, availability, and logistics is very relevant among healthcare professionals, particularly those that are directly involved in its logistics. It is paramount that SAV is handled and used appropriately. The efforts and advocacy for the availability for more SAV will be in vain if not handled appropriately before they are used. This study protocol aims to develop a tool, to assess SAV knowledge and effects of educational interventions among healthcare professionals (HCPs) in northern Nigeria. This protocol suggests conducting studies in three phases: (a) Development and validation of SAV knowledge assessment tool, (b) Baseline assessment of SAV knowledge assessment tool among HCPs, and (c) Development, implementation and evaluation of an educational intervention to improve SAV knowledge among HCPs in northern Nigeria.

Pattern of functional diversity along the elevation gradient in the dry evergreen Afromontane forest of Hararghe Highland, Southeast Ethiopia

Understanding plant species distribution patterns along environmental gradients is fundamental to managing ecosystems, particularly when habitats are fragmented due to intensive human land use pressure. The variation pattern of functional diversity of plant communities along the elevation gradient in the Dindin dry evergreen Afromontane forest was tested. Fifty four plots of 20 x 20 m (400 m2) were established at 200 m intervals starting 2,300–2,900 m a. s. l. and woody species composition, and environmental variables were recorded. Nine functional diversity indices based on functional distances were employed to esimate functional diversity. The mixed effect model was used to determine the effect of elevation, aspect and slope on functional diversity indices. The results showed that functional diversity in communities varied greatly; functional diversity revealed a decrease with increasing elevation and a‘‘humped’’ pattern, with peak diversity appearing at middle elevation. Functional diversity was significantly correlated with elevation, slope, and aspect. Functional diversity was significantly correlated with species richness and evenness. Environmental filtering was important to the functional diversity pattern; the nine indices were all successful in the analysis of functional diversity in the plant community with different effectiveness, and modified functional attribute diversity, plot-based functional diversity, community based functional diversity, functional richness, and community weight mean of woody density performed better than the other four indices in this study.

Performance assessment of the 2 γpositronium imaging with the total-body PET scanners

Purpose

In living organisms, the positron-electron annihilation (occurring during the PET imaging) proceeds in about 30% via creation of a metastable ortho-positronium atom. In the tissue, due to the pick-off and conversion processes, over 98% of ortho-positronia annihilate into two 511 keV photons. In this article, we assess the feasibility for reconstruction of the mean ortho-positronium lifetime image based on annihilations into two photons. The main objectives of this work include the (i) estimation of the sensitivity of the total-body PET scanners for the ortho-positronium mean lifetime imaging using 2γ annihilations and (ii) estimation of the spatial and time resolution of the ortho-positronium image as a function of the coincidence resolving time (CRT) of the scanner.

Methods

Simulations are conducted assuming that radiopharmaceutical is labeled with ⁴⁴Sc isotope emitting one positron and one prompt gamma. The image is reconstructed on the basis of triple coincidence events. The ortho-positronium lifetime spectrum is determined for each voxel of the image. Calculations were performed for cases of total-body detectors build of (i) LYSO scintillators as used in the EXPLORER PET and (ii) plastic scintillators as anticipated for the cost-effective total-body J-PET scanner. To assess the spatial and time resolution, the four cases were considered assuming that CRT is equal to 500 ps, 140 ps, 50 ps, and 10 ps.

Results

The estimated total-body PET sensitivity for the registration and selection of image forming triple coincidences (2γ+γ_prompt) is larger by a factor of 13.5 (for LYSO PET) and by factor of 5.2 (for plastic PET) with respect to the sensitivity for the standard 2γ imaging by LYSO PET scanners with AFOV = 20 cm. The spatial resolution of the ortho-positronium image is comparable with the resolution achievable when using TOF-FBP algorithms already for CRT = 50 ps. For the 20-min scan, the resolution better than 20 ps is expected for the mean ortho-positronium lifetime image determination.

Conclusions

Ortho-positronium mean lifetime imaging based on the annihilations into two photons and prompt gamma is shown to be feasible with the advent of the high sensitivity total-body PET systems and time resolution of the order of tens of picoseconds.

Biological and clinical significance of T helper 17 cell deficiency: insight into monogenic defects

Summary

T helper 17 (Th17) are a CD4⁺ T subpopulation cells which are involved in the host protection against microbes such as extracellular and intracellular bacteria, parasites, fungi, and viruses. Monogenic defects including those mutations in some genes such as the signal transducer and activator of transcription (STAT)1 and 3, dedicator of cytokinesis 8 (DOCK8), autoimmune regulator (AIRE), and interleukin 17 receptor A (IL-17RA) can lead to impairment in Th17 cell development and function along with the concomitant increased risk for chronic mucocutaneous candidiasis (CMC). The immunologic abnormalities in these patients include low frequency of Th17 cells; defective cutaneous or in vitro T cell response to Candida species, and/or autoantibodies against relevant cytokines. This review outlines the biological characteristics and functionality of Th17 cells, as well as the clinical features of individuals with genetic defects associated with Th17 deficiency.

P4171Population characteristics, interventions and outcomes in hospitalized orthotopic heart transplant patients with sudden cardiac arrest: a nationwide United States analysis from 2007 to 2015

Background

Sudden cardiac arrest (SCA) is a leading cause of death in the United States (US), claiming up to 450,000 lives annually and accounting for ∼25% of deaths following orthotopic heart transplantation (OHT),

Purpose

We sought to characterize OHT patients suffering SCA and their subsequent management, in comparison to the general, native heart (NH) population, using a large national inpatient database.

Methods

A cross-sectional analysis was performed among US OHT & NH patients hospitalized with incident SCA or ventricular fibrillation/flutter. We analyzed demographics, baseline characteristics, procedural utilization and outcomes. Groups were compared with standard statistical techniques. A P-value <0.05 was considered significant.

Results

From 2007–2015, 920 SCA admissions were identified among 121,083 (0.8%) OHT hospitalizations, compared to 1,731,658 (0.6%) in the general population (P<0.001). OHT patients were younger (P<0.001) and predominantly men (P<0.001). More OHT patients had diabetes (P=0.01), while the NH group had more coronary disease (P=0.01). Mechanical circulatory support use was similar in both groups overall, and OHT patients were more likely to undergo transplantation (P=0.015). Pacemaker/defibrillator implants were more common in NH than OHT patients (P<0.001). Acute kidney injury and in-hospital mortality were significantly greater in OHT patients.

Table 1. SCA in OHT & general populations Orthotopic Heart Transplant General Population P-value (N=121,083) (N=278,463,550) Sudden cardiac arrest (SCA) events, n (%) 920 (0.8%) 1,731,658 (0.6%) <0.001 Age, mean (SD) 57 (17) 66 (16) <0.001 Male sex, n (%) 644 (72%) 1,004,362 (58%) <0.001 Coronary artery disease, n (%) 275 (30%) 675,908 (39%) 0.012 Mechanical circulatory support, n (%) 64 (7%) 104,151 (6%) 0.230 Repeat heart transplantation, n (%) 5 (0.5%) 1199 (0.1%) 0.015 Pacemaker or defibrillator implant, n (%) 45 (5%) 136,314 (8%) <0.001 In-hospital mortality, n (%) 555 (60%) 932,812 (54%) 0.014 Cardiogenic shock, n (%) 78 (8%) 208,778 (12%) <0.001 Acute kidney injury, n (%) 418 (45%) 608,035 (35%) 0.003

Conclusions

SCA hospitalizations occur more often and with higher mortality in OHT patients compared to the general population. Earlier recognition of at-risk patients may result in improved utilization of potentially life-saving therapies.

A survey of pathology specimens associated with impacted teeth over a 21-year period

Background

To compare the histologic diagnosis of lesions associated with impacted teeth from a South African population with literature data.

Material and Methods

A retrospective cross-sectional survey of tissue specimens associated with impacted teeth that were analyzed in the Department of Oral Pathology (University of the Witwatersrand, South Africa) between 1996 and 2016. Patient age, gender, impacted tooth location and the histologic diagnosis were recorded for statistical analysis.

Results

Odontogenic pathology was diagnosed in 389 (95.6%) specimens while dental follicle comprised 4.4% of tissue submissions. The mean age was 25.3 ±15.2 years with a male predilection (M:F=1.8:1). The 11-20 year age group was mostly affected and the overall frequency of odontogenic lesions reduced significantly with an increase in age (p=0.01). Dentigerous cyst (56.5%) and ameloblastoma (14%) were most commonly diagnosed.

Conclusions

This is the first African epidemiologic survey of histologic specimens associated with impacted teeth and shows striking differences in the ratio of pathologic to non-pathologic diagnoses compared to other populations. Locally aggressive odontogenic lesions appear to develop one to two decades earlier in patients from developing countries.

Key words:Ameloblastoma, biopsy, dentigerous cyst, histopathology, odontogenic cyst, odontogenic tumor.

Preliminary Phytochemical Screening and Gastrointestinal Study on the Leaf Extract of Stachytarpheta angustifolia Mill Vahl (Verbenaceae) in Rabbit Jejunum

angustifolia (Verbenaceae) is mostly prescribed by the folkloric healers for various gastrointestinal disorders. This study was carried out to ascertain the gastrointestinal effect of the ethanol leaf extract and other various fractions (CHCl3, EtOAc, n- BuOH and residual aqueous) on rabbit Jejunum. The ethanol, n-butanol and residual aqueous of the extract exhibited dose concentration at (0.1, 0.2, 0.4 and 0.8 mg/ml) dependent contraction of the rabbit Jejunum which was blocked by atropine suggesting that the observed pharmacological actions was mediated through the muscarinic receptors. In contrast, chloroform and ethylacetate fraction of the leaf extract exhibit dose concentration dependent relaxation of the rabbit jejunum. Intreperitoneal LD50 of the extract in mice was found to be 295.8 mg/kg. Preliminary phytochemical screening of the leaf extract revealed the presence of carbohydrates, tannins, saponins, cardiac glycoside, sterols and terpenoids. The result indicated that, the plant extract possesses some pharmacological activity, hence justifying its use traditionally in alleviating gastrointestinal disorder.

Feasibility study of the positronium imaging with the J-PET tomograph

A detection system of the conventional PET tomograph is set-up to record data from [Formula: see text] annihilation into two photons with energy of 511 keV, and it gives information on the density distribution of a radiopharmaceutical in the body of the object. In this paper we explore the possibility of performing the three gamma photons imaging based on ortho-positronium annihilation, as well as the possibility of positronium mean lifetime imaging with the J-PET tomograph constructed from plastic scintillators. For this purposes simulations of the ortho-positronium formation and its annihilation into three photons were performed taking into account distributions of photons' momenta as predicted by the theory of quantum electrodynamics and the response of the J-PET tomograph. In order to test the proposed ortho-positronium lifetime image reconstruction method, we concentrate on the decay of the ortho-positronium into three photons and applications of radiopharmaceuticals labeled with isotopes emitting a prompt gamma. The proposed method of imaging is based on the determination of hit-times and hit-positions of registered photons which enables the reconstruction of the time and position of the annihilation point as well as the lifetime of the ortho-positronium on an event-by-event basis. We have simulated the production of the positronium in point-like sources and in a cylindrical phantom composed of a set of different materials in which the ortho-positronium lifetime varied from 2.0 ns to 3.0 ns, as expected for ortho-positronium created in the human body. The presented reconstruction method for total-body J-PET like detector allows to achieve a mean lifetime resolution of  ∼40 ps. Recent positron annihilation lifetime spectroscopy measurements of cancerous and healthy uterine tissues show that this sensitivity may allow to study the morphological changes in cell structures.

Feasibility studies of the polarization of photons beyond the optical wavelength regime with the J-PET detector

J-PET is a detector optimized for registration of photons from the electron-positron annihilation via plastic scintillators where photons interact predominantly via Compton scattering. Registration of both primary and scattered photons enables to determinate the linear polarization of the primary photon on the event by event basis with a certain probability. Here we present quantitative results on the feasibility of such polarization measurements of photons from the decay of positronium with the J-PET and explore the physical limitations for the resolution of the polarization determination of 511 keV photons via Compton scattering. For scattering angles of about 82∘ (where the best contrast for polarization measurement is theoretically predicted) we find that the single event resolution for the determination of the polarization is about 40∘ (predominantly due to properties of the Compton effect). However, for samples larger than ten thousand events the J-PET is capable of determining relative average polarization of these photons with the precision of about few degrees. The obtained results open new perspectives for studies of various physics phenomena such as quantum entanglement and tests of discrete symmetries in decays of positronium and extend the energy range of polarization measurements by five orders of magnitude beyond the optical wavelength regime.

Evaluation of Single-Chip, Real-Time Tomographic Data Processing on FPGA SoC Devices

A novel approach to tomographic data processing has been developed and evaluated using the Jagiellonian positron emission tomography scanner as an example. We propose a system in which there is no need for powerful, local to the scanner processing facility, capable to reconstruct images on the fly. Instead, we introduce a field programmable gate array system-on-chip platform connected directly to data streams coming from the scanner, which can perform event building, filtering, coincidence search, and region-of-response reconstruction by the programmable logic and visualization by the integrated processors. The platform significantly reduces data volume converting raw data to a list-mode representation, while generating visualization on the fly.

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

BACKGROUND

The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications.

METHODS

ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery.

RESULTS

The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784.

CONCLUSIONS

This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance.

CLINICAL TRIAL REGISTRATION

NCT03044899.

Top 50 Landmarks in Sentinel Lymph Node Imaging: A Bibliometric Analysis

Bibliometric analysis can be utilized to identify the most influential literature and track the trajectory of the research development in a given area. The purpose of this study is to summarize the top 50 most-cited landmarks and to examine the recent advances in the field of sentinel lymph node imaging. Web of Science was searched to create a database of all English language scientific journals. This search was then cross referenced with a similar search term query of Scopus to identify articles that may have been missed on the initial search. Articles were ranked by citation counts and screened by two independent reviewers. Citations for the top 50 papers ranged from 2725 to 163 with a median of 240. 10 papers were cited more than 500 times. The articles were published between 1993 - 2009 across 23 journals. Our study identifies intellectual milestones in Sentinel Lymph Node Imaging research, reflecting on the characteristics and quality of the most highly cited literature, and provides a list of the most influential references related to SLNI.

An outbreak of Middle East Respiratory Syndrome (MERS) due to coronavirus in Al-Ahssa Region, Saudi Arabia, 2015

Between 19 April and 23 June 2015, 52 laboratory-confirmed cases of Middle East Respiratory Syndrome due to coronavirus (MERS) were reported from Al-Ahssa region, eastern Saudi Arabia. The first seven cases occurred in one family; these were followed by 45 cases in three public hospitals. The objectives of this investigation were to describe the epidemiological characteristic of the cluster and identify potential risk factors and control measures to be instituted to prevent further occurrence of MERS. We obtained the medical records of all confirmed cases, interviewed the members of the affected household and reviewed the actions taken by the health authorities. All the cases were connected. The index case was a 62-year-old man with a history of close contact with dromedary camels; three of the seven infected family members and 18 people in hospitals died (case-fatality rate, 40.4%). The median incubation period was about 6 days. The cluster of cases appeared to be due to high exposure to MERS, delayed diagnosis, inadequate risk communication and inadequate compliance of hospital health workers and visitors with infection prevention and control measures.